blueprinting v8 engine (for Porsche 944 - goal: 400 rwhp but still maintain 35mpg)

[bp944]

I did some more looking at I can get the gear ration very near to what I want. I can take the 6 speed transmission from a 968 and get a custom ring and pin. That will set me somewhere around 1200 rpm for cruising at 65.

I mentioned earlier that I would not touch a turbo kit but I realized there might actually be room for a turbocharger in the car. How would I use a turbo charger to pull out good gas mileage?

[serialk11r]

A turbo increases gas mileage if you downsize the engine and then use the turbo to match the power. It's very hard to increase fuel economy by adding a turbo, unless you have "lossless throttling" (aka Valvetronic, VVEL, Valvematic, Multiair), where the boost the turbo builds will reduce compression work.

1200rpm is frighteningly low! How are you going to do that? I see that there are 3.250 final drives that will get you down to ~2000rpm or so, how are you going to get it to 1200? O_O

[bp944]

That was a number someone threw out on rennlist (a porsche forum). The custom ring and pinion can be between 3.0 and the 3.44. The audi 2wd diesel has a 5th gear of .729 and a 6th gear of .600 that will fit into the 968 box. That doesn't seem to work out to be the 1000 rpm but more around 1900 if my math is right which is probably not. Transmissions are something I haven't spent much time looking into, if you haven't figured that out yet.

[serialk11r]

Whoa. 3.0 and 0.600 works out to be ~1500 rpm at 60 I think. Somewhere around there, too lazy to look up the tire size. That's quite good.